Section 4(1)(a) in The Merchant Shipping (Control of Pollution by Noxious Liquid Substances in Bulk) Rules, 2010
(a)where any amendment to these rules and the International Bulk Chemical Code or the Bulk Chemical Code involves changes to the structure, equipment and fittings due to the upgrading of the requirements for the carriage of certain substances, the Central Government may, having regard to each substance, either modify the requirements for their carriage or delay application of such requirements, to ships constructed before such amendment has come into force, for a specified period, if it deems that application of such amendments is unreasonable or impracticable;